The invention relates to trailer jacks and more particularly, to a trailer jack with a locking mechanism for the locking of the jack in position.
The invention, although having broad application to a wide variety of structures, is particularly suited to two or more wheeled trailers of the type which are often drawn by powered vehicles such as jeeps, and carry relatively complex and sensitive electronic equipment such as radar systems. These trailers many times require leveling and stabilization when the electronic equipment is in use. For this purpose, jacks are attached to various points on the trailer and are deployed when the electronic equipment is in use.
As a specific example, trailers carrying radar equipment including precision antennas and signal processing equipment, must in some cases be towed to positions in rugged terrain. While towing, it is desirable that all equipment of the trailer, such as jacks, be stowed and positively locked in position so as to not interfere with travel over the rugged terrain. When arriving at the selected position, the jacks must be capable of being rapidly deployed and of leveling the trailer in the rough terrain. In certain applications, it is also a requirement that the jacks be capable of maintaining the trailer in a stabilized position during operation of the electronic equipment.
To accomplish the above, the jack must be capable of being locked in position quickly and positively and once locked, the locking mechanism must be such that there is no looseness between the jack and the trailer so that operation of the electronic equipment does not cause trailer instability. In addition, some applications require that the jack and locking mechanism must be capable of being deployed and stowed numerous times and in many different environments including mud, snow, low and high temperatures, rain, etc., without degradation.
Prior techniques for jack locking mechanisms include spring loaded detent blades with detents in a bearing plate such as that shown in U.S. Pat. No. 3,033,523; locking pins with securing devices such as that shown in U.S. Pat. No. 2,885,181; and spring loaded pins which are permanently mounted on the jack structure and extend into sockets in the trailer frame. The above techniques are generally applicable to light duty trailers where a wide variety of environmental conditions is not encountered, and where absolute stability during jack deployment is not an absolute requirement. When exposed to extreme types of environmental conditions such as mud, ice, snow, etc., prior locking mechanisms would jam in some cases. In order to break the jammed locking mechanism free, extreme force would be applied in some cases and this would result in deformation of the locking mechanism. Also, due to the basic design of prior locking mechanism structures, close tolerances were not maintainable over numerous uses of the jack with the result of a loose jack even when locked in position. In some cases, in particular in the spring loaded techniques, safety problems have occurred. Due to prior applications of force to free the locking mechanism, deformation of parts resulted and the spring was not sufficiently strong enough to lock the jack in position in extremely rugged terrain.